Trace

The Trace tab allows one to set the color,
size, and transparency of the tiles by the color or transparency of
the objects (including bitmaps) that are placed under the location
of the tiling. To enable this feature, the Trace the drawing
under the tiles box must be checked.

The Trace tab has three sections. At the top
is a section for specifying what property of the underlying drawing
should be used for input. Options include the color, one of the
RGB components, or one of the HSL
components. There is also the option to use the
Opacity, which is the sum of the opacities
(Alpha) of all
objects under the tile.

In the middle of the tab is a section to modify the input value.
One can specify a Gamma[15]
correction or add a randomization factor to the input. One can also
invert the input.

The bottom section is for specifying what should be affected by
the input. Options include Presence (the
probability that a given tile will be drawn), color, size, and
opacity. The color will only be changed for regions of the base
tile that have Unset fill.

The Trace tab of the Tile Clones dialog.

The following figures show the effect of some of the possible
combinations of input and output options. All the figures use the
first rainbow figure as the input drawing. The rainbow is a
radial gradient with multiple stops. The
inside of the rainbow is defined as a white gradient stop with zero
Alpha. The last outside stop is defined with a
red color and with zero Alpha. For most
figures, a star inside an unfilled rectangle is used as the base
tile. The star has been given an Unset fill
when color is selected in the output.

The rainbow pattern used for the background (a radial gradient).

Input: Color. Output: Presence.

Input: Color. Output: Color. Background rainbow has been removed.

Input: Color. Output: Size.

Input: Color. Output: Opacity.

Input: Hue. Output: Size. Note how the red has a hue of zero and purple has
the maximum value.

Input: Color, 10% random gamma. Output Color. Changes made to other tabs:
Shift: −20%, random 10%, Rotation: random 20%. The number of rows and columns
has been increased to compensate for the shift. The background rainbow has
been deleted.